The present invention relates to an automatic air bleeding device for a fuel feed system of a diesel engine.
In general, as shown in FIG. 1, a fuel feed system of a diesel engine comprises a fuel tank 1, a water separator 2, a feed pump 3, a fuel filter 4, an injection pump 5 and an injection nozzle 6.
During the operation after the starting of the engine, the fuel in the fuel tank 1 is sucked by the feed pump 3 to be fed through the water separator 2 for separation of water contained in the fuel into a gallery chamber 3a which has a plunger and springs (not shown) and which is disposed within the feed pump 3 and is filtered by the fuel filter 4 to flow into the injection pump 5 where the fuel is forced to pass to the injection nozzle 6 which is connected to a cylinder head (not shown) so that the fuel is injected under controlled pressure into a combustion chamber (not shown).
The injection pump 5 is provided with an overflow valve 8 which is adapted to control the pressure of the fuel to be fed to the injection pump 5 at a predetermined pressure. More specifically, when the pressure of the fuel is in excess of a predetermined level, the overflow valve 8 is opened to return the fuel through the overflow pipe 9 into the fuel tank 1.
Reference numeral 10 represents a leakage pipe for returning to the fuel tank 1 the fuel which has lubricated a nozzle needle of the injection nozzle 6.
With the diesel engine having the fuel feed system of the type described above, when air intermixes in the fuel feed system due to emptiness of the fuel tank, replacement of the fuel filter 4 or the like, the fuel supply from the feed pump 3 to the injection pump 5 is not stabilized and the engine starting failure occurs. Therefore when the fuel feed system contains the air, before starting of the engine an air bleeding plug 11 is loosened and a driver operates a manually operated priming pump 12 until fuel free from air bubbles begins to flow through the air bleeding plug 11. Such manual operation casts a cumbersome burden to a driver.
In view of the above, the present invention has its object to provide an automatic air bleeding device for a fuel feed system of a diesel engine which can considerably relieve a driver's burden in air bleeding operation.
The above and other objects, effects, features and advantages of the present invention will become more apparent from preferred embodiments thereof taken in conjunction with the accompanying drawings.